Petroleum distillates containing butadiene-styrene copolymers



United States Patent 3,419,365 PETROLEUM DISTILLATES CONTAINING BUTADIENE-STYRENE COPOLYMERS William L. Streets, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware No Drawing. Filed Nov. 21, 1966, Ser. No. 595,614 9 Claims. (Cl. 44-62) ABSTRACT OF THE DISCLOSURE This invention relates to improved petroleum distillates. In one of its aspects, it relates to a petroleum distillate having an improved pour point and/or improved resistance to thermal degradation. In another of its aspects, the invention relates to the treatment of a petroleum distillate to improve its pour point and/or resistance to thermal degradation. Further, the invention relates to petroleum distillate fuels having the improved properties mentioned.

In one of its concepts, the invention provides a hydro carbon liquid containing a small proportion of a hydrogenated butadiene-styrene random or block copolymer which imparts thereto an improved pour point and/ or increased resistance to thermal degradation. In another of its concepts, the invention provides a process for the modification of the properties of a liquid hydrocarbon by incorporating therein a small amount of a hydrogenated butadiene-styrene random or block copolymer. In a further concept of the invention, the copolymer is first incorporated into an oil whereupon the oil containing the additive is incorporated into the liquid hydrocarbon or distillate.

It is well known that hydrocarbon liquids should be pourable and/or pumpable at low temperatures. A number of additives have been proposed for use in these hydrocarbon liquids to achieve this flowability. However, it has been found that not all hydrocarbon liquids respond to such pour point depressants. For example, pour point depressants which have great success in reducing the pour point of lubricating oils have frequently been ineffective in reducing pour point of distillate fuels. Indeed, even those depressants which have success with some distillate fuels fail completely when used with distillates from another source. Because some distillate fuels do not respond to known pour point depressants, the commercial pour point requirements must be met by other means, such as by blending in large amounts of petroleum fractions which may have lower pour points but which are more expensive. For example, kerosene is frequently used to reduce the pour point of furnace oils and diesel fuels.

I have now found that hydrogenated butadiene-styrene copolymers as described herein are effective to reduce the pour point of a wide variety of liquid hydrocarbons, such as petroleum distillates, for example petroleum distillate fuels.

An object of this invention is to provide an improved hydrocarbon product. Another object of the invention is to provide an improved hydrocarbon distillate product. A further object of the invention is to provide an improved petroleum distillate product. A still further object of the invention to provide an improved hydrocarbon distillate fuel product. Yet another object of the invention is to provide an improved petroleum distillate fuel product. A further object of the invention is to provide a liquid hydrocarbon product having improved pour point. A still further object of the invention is to provide a liquid hydrocarbon product having increased resistance to thermal degradation. A still further object of the invention is to provide a product containing at least a liquid hydrocarbon and an additive yielding stability to said hydrocarbon on storage.

Other concepts, objects and the several advantages of the invention are apparent from a study of this disclosure and the claims.

According to the present invention, there is provided an improved product containing a liquid hydrocarbon and a small amount of a hydrogenated butadiene-styrene copolymer as herein described.

The use of the additives according to the invention can eliminate a portion or all of the pour point depressants formerly used. Thus, according to the invention, large amounts of petroleum fractions, for example kerosene, can be diverted for other more important uses.

Advantageously the use of the additives of the invention, in the case of distillate fuels, yields compositions having a higher heating value and higher cetane number.

Further, distillates or fuels treated with the additives of the invention are found more stable to degradation as on storage. Thus, on aging, such fuels develop less color and form less insoluble materials.

At present, the additives of the invention are usually employed in an amount in the approximate range 0.005 to 0.5 weight percent of the distillate or fuel or other hydrocarbon liquid. One skilled in the art in possession of this disclosure having studied the same can routinely determine the optimum proportion of copolymer for his purposes.

The hydrogenated copolymers or additives of the present invention have a molecular weight in the approximate range of from about 2000 to about 200,000, a now preferred range being from about 5000 to about 100,000 and a now still more preferred range being from about 25,000 to about 50,000, The copolymers can be one containing from about 2 to about 98 parts by weight of styrene per hundred parts by weight of monomers. Thus, the broad range of the butadiene-styrene ratio in the copolymer can extend from about 98:2 to about 2:98, but now from about 60:40 to about 90:10 is preferred with particularly satisfying results being obtained with a copolymer having a :25 ratio.

The hydrogenated copolymer molecular weight referred to throughout this application refers to number-average molecular weight. The number-average molecular weight of a specific butadiene-styrene copolymer is determined by methods which are conventional in the art. For example, a particularly convenient method for determining the molecular weight of copolymers in the 15,000 to 200,000 range is by the membrane osmometer. Such a procedure is described in a paper by R. E. Steele et al. at the Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy in March 1963. For copolymers in the 5,000 to 15,000 range, ebullioscopic methods are appropriate, such as the technique described by R. L. Arnett et al. in the Journal of Polymer Science, Part A, Vol. I, pp. 2753-2764 (1963). For copolymers having molecular weights below 5,000, methods employing the use of a vapor pressure osmometer such as that available from Mechrolab Inc., 1062 Linda Vista Ave., Mountain View, Calif, are appropriate.

The hydrogenated copolymers of the present invention can be prepared by any of the conventional techniques known in the art. For example, the hutadiene-styrene mixture of monomers can be polymerized using butyl lithium as the catalyst. The hydrogenation can be carried out over a nickel octoate-triethylaluminum catalyst system. U.S. Patent 2,864,809, R. V. Jones et al., issued Dec. 16, 1958, describes a technique for hydrogenating 'butadiene-containing polymers. The hydrogenated butadiene-styrene copolymers of the present invention are polymers which have been sufiiciently hydrogenated to remove substantially all of the olefinic unsaturation leaving only the aromatic unsaturation.

For convenience in handling, the above-described copolymers can be dispersed in a carrier such as a low viscosity lubricating oil stock, a hydrocarbon solvent such as cyclohexane, or any inert diluent in which the additive is sufiiciently soluble. The use of an oil, as earlier indicated, is now preferred. The pour point depressant additive of the present invention is generally added to the petroleum distillate fuels in amounts which range from about .005 to about 0.5 weight percent (exclusive of carrier) based on the weight of the fuel. Conventional techniques for dispersing the additives in the distillate fuels can be used.

The distillate fuels to which the present invention is applicable include such petroleum fractions or catalytically modified fractions or mixtures thereof which boil at temperatures in the range of from about 70 to about 750 F. These fuels include gasolines, such as aviation, marine, and automotive gasolines, jet fuels, diesel fuels, heating oils, and the like.

In addition to the additives of the present invention, the treated petroleum distillate fuels can also contain other commonly used ingredients such as anti-oxidants, colorants, combustion improvers, anti-knock compounds, and the like.

The table below shows the results of this additive treatment.

TABLE I.POUR POINT ASTM D 97-57 (F.)

Treated with 0.18 Wt. percent Distillate Fuel Stock Untreated Invention Additive 1 25,000 M01 Wt. 100,000 Mol Wt.

75:25 Butadiene: Styrene Hydrogenated Random Copolymer having indicated molecular weight.

The data in the table above show that treatment of the distillate fuel stocks with the additives of the present invention resulted, in every case, in a substantial decrease in the pour point temperatures.

Example ll Another series of tests were carried out to demonstrate still another advantage of the additives of the present invention. The ability of the additives to improve the heat stability of a number of fuel blends was shown. The same two hydrogenated random copolymers, described in Example I, were also used in these tests in concentrations of 0.18 weight percent of active ingredient based on the weight of the fuel.

In the ASTM Color test, the fuels were heated to 300 F. for a period of 90 minutes. After the heating period the fuels were subjected to a color determination, the higher numbered color rating indicating the greater amount of color present.

In another heat stability test, the fuel blends containing the invention additive were given the Nalco 300 F. Tes which is described in Du Pont Petroleum Laboratory Test number F2l-61, dated December 1962. In this test the fuel is subjected to a heat treatment and then filtered to determine the amount and color of any insoluble material formed. The higher numbered filter ratings indicate greater quantities of insolubles present.

The results of both of these tests on the distillate fuel 45 blends are shown in Table II below.

TABLE II ASTM D 1500-58T Naleo Distillate Fuel Blend Additive 1 Treatment; Color Test Filter Ratlng Before After Cet-ane Index..." None 2.0 L5. 0 15 K Blend of Distillate" 25,000 M.W. Copolymer.-. L2. 0 2. 5 5 Stocks A and B--. 100,000 M.W. Copolymer L2. 0 3. 5 7 50 Cetane Index... None 1. 5 3. 5 9 L Blend of Distillate.-. 25,000M.W. copolymer--. L2. 0 2. 5 4 Stocks C and D 100,000 M.W. Copolymer" 1. 5 2. 5 4 50 Cetane Index. None 1.0 5.0 20 M Blend of Distillate... 25,000 M.W. copolymer--. 1.0 2.0 5 Stocks E and F 100,000 M.W. Copolymer-- 1.0 2. 5 7 50 Cetane Index. None L1. 0 2.0 9 N Blend of Distillate.-- 25,000 M.W. Copolymer..- L1. 0 L1. 0 3 Stocks G and H-..- 100,000 M.W. Gopolymer-- 0.5 L1. 5 5 50 Cetane Index..." None L1. 5 L3. 0 6 0 Blend of Distillate..- 25, 00 M.W. Copolymer... L1. 5 L2. 5 4 Stocks I and I 100,000 M.W. Copolymen. L1. 5 L2. 5 3

0.18 weight percent based on the fuel of a :25 butadiene:styrene random copolymer having indicated molecular weight.

Example I The data in the table above show that, without exception, the polymeric additives of the present invention stabilized both the color and the insolubles formation of all the fuel blends.

Example III The distillate fuel blends described in Example 11 were tested for response in regard to pour point depression using various levels of the invention additive. The additive was a hydrogenated, 25,000 molecular weight random butadiene: styrene copolymer in which the ratio f the butadiene to styrene was 75:25. The results of this series of tests are shown in the table below.

TABLE III Hydrogenated, 25,000 M.W. 75:25

Distillate Butadiene:styrene Random Copolymer, Wt., Percent Fuel Blend None 0. 0225 0. 045 0. 0575 0. 09 0. 135 0. 18

The data in the table above show that the additive of the invention is effective in depressing the pour point of each of the varied distillate fuel blends. It is seen that some distillate fuel blends showed excellent response with as little as 0 0225 weight percent of the additive, based upon the weight of the fuel.

Example IV TABLE IV.POUR POINT F.)

The data in the table above show that the molecular weight and the butadiene-styrene incorporation can be significantly varied while still providing an effective additive for the pour point depression of a number of varied distillate fuel blends.

Exanple VI To further demonstrate the effectiveness of the fuel additives, a number of fuel blends containing these additives were subjected to the Enjay Fluidity Test ELD 48439, dated Jan. 29, 1964. In this test, a sample of the treated fuel is cooled to a 38 F. and then allowed to flow through a constriction. The percentage of fuel which passes the constriction within a three minute period is recorded. For purposes of comparison, a widel used commercial Additive X, believed to be a copolymer of ethylene and vinyl acetate, was also tested.

The results of these tests are shown in Table VI below.

Distillate Fuel 0.09 Wt. Percent 0.08 Wt. Percent Blends Invention Commercial Additive 1 Additive X" A 25,000 molecular weight, 75:25 butadiene:styrene random 00- polymer.

Treated with 90: 10 Butadiene:Styrene Hydrogenated Random Copolymer Distillate 1gueld Untreated 25,000 Mol Wt. 100,000 Mel Wt.

0.045 Wt. 0.09 Wt. 0.18 Wt. 0.045 Wt. 0.09 Wt. 0.18 Wt. Percent Percent Percent Percent Percent Percent The data in the table above show again that small amounts of the invention additive are successful in significantly depressing the pour point of a distillate fuel.

Example V A number of other tests were carried out to demonstrate the variations possible in the invention additive. Hydrogenated random copolymers of butadiene and styrene having different molecular weights and different proportions of butadiene and styrene were tested. The tests for pour point depression were similar to those in preceding examples using the previously described distillate fuel blends.

The results of this series of tests are shown in Table V below.

The results in the table above show a substantial improvement in the fluidity of the fuels treated with the invention additive when compared to the same fuels treated with the commercial additive. The untreated fuels, of course, exhibit no flow at all under these conditions.

Example VII Several tests were carried out to show that, to be effec tive, the additives of the present invention must be copolymers and that they must be hydrogenated.

The previously described distillate fuel stock B was treated with 0.1.8 weight percent, based on the weight of the fuel stock, of a 35,000 molecular weight hydrogenated polybutadiene homopolymer. The pour point of the fuel stock treated in this manner Was found to be 0 F.,.com-

A random copolymer of butadiene and styrene having the indicated molecular weight and butadiene-styrene incorporation.

7 paring with F. of the untreated fuel stock. This fuel was considered non-depressed, these two temperatures being within the 5 F. reproducibility range of the ASTM procedure. The poor performance even at the relatively high loading level of 0.18 weight percent also shows that 8 stripped from the hydrogenated polymer and replaced with a SAE stock neutral oil such that the polymer made about a 10 weight percent solution in this neutral oil carrier.

Simple block copolymers of butadienc-styrene were prea such an additive is essentially ineffective. pared according to procedures essentially identical with In another test, a random copolymer having a 25,000 that described above except that the tetrahydrofuran ranmolecular weight and a 75:25 ratio of butadienezstyrene domizing agent was omitted. was tested. This copolymer was essentially identical to Table A below contains a description of some of the that used in a number of preceding examples with the exdistillates used in the testing of the invention.

TABLE A Viscosity, Wax Content, Distillation, F. Distillate Fuel Stock API Centistokes Wt. Percent Gravity at 100 F. Normal Initial 10% 50% 80% El Paraflins A Diesel Base from Refinery No. l 87. 3 3. 57 20. 6 344 402 542 560 638 B Light Cycle on from Refinery No. 1 25.3 3.32 15.0 440 504 540 570 618 C Diesel Base from Refinery No. 2. 36. 7 3. 41 23. 0 425 494 538 504 609 D Light Cycle on from Refinery No. 2. 25. e 3. 00 14. e 469 501 527 554 603 E Diesel Base from Refinery N0. 3. 39. 3 2. 66 23.2 415 469 504 527 570 F Light Cycle on from Refinery N0. 3.. 29. 2 1e 1e. 6 463 500 535 566 519 G Diesel Base from Refinery No. 4. 36. 4 l9. 3 364 446 513 550 612 H Light Cycle Oil from Refinery No. 4-. 31. 5 14. 4 389 453 515 550 610 I.-- Diesel Base from Refinery No. 5 38. 6 20. 0 416 476 525 560 619 .1 Light Cycle Oil from Refinery No. 5 28.9 15.1 423 494 543 570 625 Diesel base is straight run distillate.

ception that it was not hydrogenated. When tested in distillate fuel stock B, at an 0.18 weight percent level, the pour point of fuel stock treated in this manner was found to be 0 F. and thus considered non-depressed for reasons mentioned in the preceding paragraph.

Example VIII Another series of tests was carried out to show that a hydrogenated, simple block copolymer of butadiene and styrene is also effective in depressing the pour point of a distillate fuel. A distillate fuel stock was treated, at an 0.18 weight percent level, with several variations of such a hydrogenated, simple block copolymer. The results of the pour point determination on these treated fuels are 1 A hydrogenated, simple block copolymer of butadiene-styrene having the indicated molecular weight and butadiene-styrene incorporation.

The data in the table above show that hydrogenated, simple block copolymers of butadiene and styrene are also effective in significantly depressing the pour points of a distillate fuel.

Example 1X The following is a description of a typical preparation of a hydrogenated 25,000 molecular weight random copolymer having a butadiene:styrene ratio of 75:25.

A dry 26-ounce bottle was charged with 400 g. cyclohexane, purged with nitrogen, capped, and then charged, by syringe, with 37.5 g. butadiene, 12.5 g. styrene, 0.75 g. tetrahydrofuran, and 2.2 millimoles of secondary butyllithium. The bottle was placed, for 2 hours, in a constant temperature bath maintained at 122 F.

After the reaction period, the polymer-containing solution was then drawn into a hydrogenation pressure vessel where it Was contacted for two hours at about 350 F. with 400 p.s.i.g. hydrogen pressure in the presence of a hydrogenation catalyst comprising 12 ml. of nickel octoate solution (containing 0.0061 g. Ni/ml.) and 5 ml. of triethylaluminum.

After examining a sample of the hydrogenated polymer by infrared absorption to assure complete hydrogenation of the acyclic unsaturation, the cyclohexane diluent was Throughout the examples the additives were added to the fuels in a 10 stock neutral oil in about a 10 percent by weight concentration. All of the loading levels shown in the examples, however, are in weight percent of the active ingredient, that is, the polymer only.

One skilled in the art in possession of this disclosure having studied the same will understand that the amount of the additive as well as its specific character can be selected for best results in view of the hydrocarbon liquid which it is desired to improve, and that the selection will be made further in View of the kind, as well as amount of improvement sought to be effected. Variation in the compounding of a product according to the invention is possible. A priori, simultaneous or subsequent treatments may be effected together with the incorporation of the additive of the invention.

Among the distillates which are applicable for use in the present invention are the following Distillate: Boiling range (initial-final) F. Gasolines 70-420 Jet fuels -500 Diesel fuels 350-625 Heating and stove oils 350-570 High boiling distillate fuels 400-750 Reasonable variation and modification are possible in the scope of the foregoing disclosure and the appended claims to the invention, the essence of which is that a hydrogenated styrene-butadiene copolymer has been incorporated into a liquid hydrocarbon obtaining improved properties and advantages as set forth and described.

I claim:

1. A composition suitable for use as a fuel, said composition containing a liquid hydrocarbon distillate and a small amount effective to act as a pour point depressant and/or a thermal degradation inhibitor of a hydrogenated styrene-butadiene copolymer additive having a molecular weight in the approximate range 2,000 to 200,000.

2. A product according to claim 1 wherein the additive is selected from random and block copolymers of butadiene and styrene and is present in an amount in the approximate range 0.005 to 0.5 weight percent of the liquid hydrocarbon distillate.

3. A product according to claim 2 wherein the copolymer has a molecular weight in the approximate range 2000 to 200,000.

4. A product according to claim 2 wherein the copolymer has a molecular Weight in the approximate range 5000 to 100,000.

5, A product according to claim 2 wherein the copolymer has a molecular weight in the approximate range 25,000 to 50,000.

6. A product according to claim 1 wherein the distillate is a petroleum distillate and is at least one 'of a gasoline, a jet fuel, a diesel fuel and a heating oil.

7. A product according to claim 6 wherein the fuel boils at temperatures in the range of from about 70 to 750 F.

8. A product according to claim 7 wherein the additive is prepared by copolyrnerization using a butyllithium catalyst and the hydrogenation is effective to remove substantially all of olefinic unsaturation.

9. A composition according to claim 1 wherein said liquid hydrocarbon distillate is selected from the following:

gasolines which boil in the range 70-420 F.;

jet fuels which boil in the range 120-500 F.;

diesel fuels which boil in the range 350-640 F heating and stove oils which boil in the range 350-570 F.; and

high boiling distillate fuels which boil in the range 400- DANIEL E.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 3/1957 Great Britain. 9/1960 Great Britain. 10/ 1963 Great Britain.

WYMAN, Primary Examiner.

W. J. SHINE, Assistant Examiner.

US. Cl. X.R. 

